Sorption of Gases and Organic Vapors

The present chapter deals with several aspects of adsorption of gases and organic solvent vapors onto Styrosorbs 1 and 2. Most of the adsorption experiments were carried out shortly after the development of hypercrosshnked polystyrene materials. The choice of sorbates was largely dictated by practical needs. Sorption of hydrocarbons and their chloro and fluoro derivatives as well as vapors of organic solvents was thought to be... 

Chapter 4(71) focuses on the characterization of sorption kinetics in several glassy polymers for a broad spectrum of penetrants ranging from the fixed gases to organic vapors. The sorption kinetics and equilibria of these diverse penetrants are rationalized in terms of the polymer-penetrant interaction parameter and the effective glass transition of the polymer relative to the temperature of measurement. The kinetic response is shown to transition systematically from concentration independent diffusion, to concentration dependent diffusion, and finally to complex nonFickian responses. The nonFickian behavior involves so-called "Case II" and other anomalous situations in which a coupling exists between the diffusion process and mechanical property relaxations in the polymer that are induced by the invasion of the penetrant (72-78). ... 

CDs can form inclusion complexes with iodine, which makes them candidates for iodine-sorption from nuclear waste gases. In model experiments, it was shown that the aqueous solutions containing CDs and crosslinked CD polymers were selective and effective iodine absorbers [86]. Especially the cr-CD derivatives (methylated and crosslinked) have high sorption capacity. On the basis of the results, the binding of elemental and organic iodine emitted into the air by chemical and nuclear power plants can be made effectively by immobilizing iodine vapor in aqueous CD solutions or in CD polymer gel beds. Such new sorbents can be employed in the air filtration systems (Table 8.4). 

Sorption of gases, vapors, or organic permeants into semi-crystalline polymers is mainly described and modeled as a function of different factors or parameters... 

The bulk of UPS literature has appeared since 1970, and it has concentrated in two areas (1) interpreting spectra of organic vapors and (2) studing transition metal electronic band structure changes caused by sorption of simple gases on the metal surfaces. Interpreting uv photoelectron spectra is very difficult and until a data base of spectral measurements is accumulated, it will be used infrequently in surface chemical studies. 

Sorption and diffusion in polymers are of fundamental and practical concern. However, data acquisition by conventional methods is difficult and time consuming. Again, IGC represents an attractive alternative. Shiyao and co-workers, concerned with pervaporation processes, use IGC to study adsorption phenomena of single gases and binary mixtures of organic vapors on cellulosic and polyethersulfone membrane materials (13). Their work also notes certain limitations to IGC, which currently restrict its breadth of application. Notable is the upper limit to gas inlet pressure, currently in the vicinity of 100 kPa. Raising this limit would be beneficial to the pertinent use of IGC as an indicator of membrane-vapor interactions under conditions realistic for membrane separation processes. 

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